1. Field of the Invention
The present invention relates to a method of producing semiconductor components with at least one junction and at least one weak N- or P-conducting zone containing 10.sup.13 to 2.5 .times. 10.sup.14 doping atoms/cm.sup.3. More particularly, the present invention relates to the doping of semiconductor substrates having the above-described characteristics by diffusing appropriate doping atoms into individual zones in the substrate from a layer of nickel containing an appropriate doping material and deposited on one of the semiconductor crystal surfaces.
2. Description of the Prior Art
A prior art method of doping semiconductor substrates with an appropriate dopant material is known in which a nickel film containing the desired dopant is deposited on the semiconductor body by the electroless autocatalytic reduction of a nickel salt with a boron compound in the same solution. The method is described in German Pat. No. 2,144,018. The semiconductor substrate covered with the doped nickel layer is then subjected to inward diffusion of the boron contained therein at temperatures between 800.degree. and 1400.degree. C.
In another technique, an N-doped zone is provided in a semiconductor substrate as disclosed in German Pat. No. 1,816,082 by chemically depositing a phosphorous containing nickel film of the substrate and then heat-treating the substrate. One particular advantage of this process is that the nickel layer which functions as the diffusion source can be deposited electrolessly at low temperature, thereby eliminating the evaporation step which requires a large amount of power. However, up to the present time, no successful method has been known in which this technology can be used for the fabrication of semiconductor devices having voltage capacities above 2500 V. These devices normally require correspondingly thicker and deeper-ohmic semiconductor wafers.
A need, therefore, continues to exist for a technique of forming semiconductor devices having voltage characteristics above 2500 V in which the dopant atoms are diffused from a covering nickel film.